F-16 autopilot ATT Hold and ALT Hold do not work

[septimusthehoplite]

When I flick the autopilot switch into Alt hold the plane will keep claiming or descending and ATT hold will also not hold an attitude of the jet. The heading and steering on the roll switch do work though. I have ruled out my HOTAS by testing with it unplugged. I have also tested my paddle switch. It works normally when I have the roll set to heading and steerpoint and deactivates fine when depressed and when released the plane goes back to the heading. When I just use Alt and Att hold the paddle has no effect due to the main issue. Fuel door is closed, gear is up, and trim autopilot disconnect is set to norm. The issue happens on hot and cold start so nothing with the alignment is causing it. The switch is also staying in position so the jet isn't turning it off either. Anyone got other ideas?

[rob10]

1 hour ago, septimusthehoplite said:

When I flick the autopilot switch into Alt hold the plane will keep claiming or descending and ATT hold will also not hold an attitude of the jet. The heading and steering on the roll switch do work though. I have ruled out my HOTAS by testing with it unplugged. I have also tested my paddle switch. It works normally when I have the roll set to heading and steerpoint and deactivates fine when depressed and when released the plane goes back to the heading. When I just use Alt and Att hold the paddle has no effect due to the main issue. Fuel door is closed, gear is up, and trim autopilot disconnect is set to norm. The issue happens on hot and cold start so nothing with the alignment is causing it. The switch is also staying in position so the jet isn't turning it off either. Anyone got other ideas?

People will have a much better idea if you post a (short as possible) track.  You can save a track file from the debrief screen after you end the mission.

[LeCuvier]

I have not flown the F-16 recently. When I did in the past, I always found that the AP was working.
When I saw this thread I decided to give it a try, and I could not get the AP to work the way I had experienced earlier. Even after setting a 5% deadband on the pitch axis, I could not see the pitch AP kick in. The AP switches in the sim do respond to my switch inputs.

[cesarferrolho]

That's odd.

I just tested real quick and every AP mode is working for me. Also working: automatic steerpoint switching and the AP disengage lever/button on the stick

[LeCuvier]

I re-tested today and found the AP working fine. I could not find any of my HOTAS switches making a difference. So that's a bit mysterious.
Note: Two days ago, I had increased the pitch axis deadband to 5% and it was still not working. Today I reduced the deadband to 2% and I could get the AP to kick in. 1% wouldn't work.
I then re-calibrated my joystick, and reduced the deadband to 1% and the AP still works.

My conclusion: people struggling to make the AP engage should should make sure their stick is well calibrated and, if that's not enough, increase the deadband.
The failure I experienced 2 days ago would not be fixed by that approach though. It remains unexplained.